1. Field of the Invention
The present invention generally relates to a sense amplifier of a nonvolatile ferroelectric memory device, and more specifically, to a sense amplifier which improves amplification by doubly regulating a level of a sensing voltage depending on sensed data.
2. Description of the Prior Art
Generally, a ferroelectric random access memory (hereinafter, referred to as ‘FeRAM’) has a data processing speed as fast as a Dynamic Random Access Memory (hereinafter, referred to as ‘DRAM’) and conserves data even after the power is turned off.
The FeRAM having structures similar to the DRAM includes the capacitors made of a ferroelectric substance, so that it utilizes the characteristic of a high residual polarization of the ferroelectric substance in which data is not deleted even after an electric field is eliminated.
The technical contents on the above FeRAM are disclosed in the Korean Patent Application No. 1999-14400 by the same inventor of the present invention. Therefore, the basic structure and the operation on the FeRAM are not described herein.
As a chip operating voltage of the FeRAM becomes lower, a cell sensing voltage is reduced, so that it is difficult to embody the rapid operation speed.
When a cell data sensing voltage is small, a voltage margin for detecting timing is also small, so that it is difficult to sense the voltage. As a result, reduction of the sensing margin by generation voltage variation of the timing sensing voltage occurs.